Useful DAQ commands
Compile command
gcc -o outfile filename.c /usr/local/lib/gpib/cib.o -lm
The following commands are for system setup, and are generally used once at either
the beginning or end of the program. Except for the buffer clear command.
This command creates a pointer for the data output file
FILE *fp;
Opens file in the append mode. If file is not opened in the append mode, it will overwrite
what is currently in the file.
fp=fopen(“filename.dat”,”a”);
Tells PC the address of the data acquisition unit.
DAQ = ibdev(0, 10, 0, 10, 0, 1);
Clears output buffer if DAQ. This command must be executed before each scan, or
errors will occur in your data.
ibclr(DAQ);
Tells DAQ that it will operate in GPIB mode. This command is done once near the
beginning of the program.
ibwrt(DAQ, “SYST:INT GPIB \n”, 16L);
Close data file.
fclose(fp);
Take DAQ offline.
ibonl(DAQ,0);
The following commands are used for the actual taking of data, and are repeated for
however many channels are being used.
NOTE: remember to clear output buffer before each scan.
Configure channel 01 of card 1 to temperature measurement using type K thermocouple.
The first number of 101 is the slot card, the second and third numbers are
the channel number.
ibwrt(DAQ, "CONF:TEMP TC,K,(@101) \n", 24L);
Follow with to give equipment time to respond to configuration command.
sleep(2);
Set the length of time that DAQ samples input.
ibwrt(DAQ, "SENS:TEMP:NPLC 20,(@101) \n", 27L);
Tell the DAQ which channel to monitor for input.
ibwrt(DAQ, "ROUT:SCAN (@101) \n", 18L);
Initiate scan.
ibwrt(DAQ, "INIT \n", 7L);
This sleep allows the scan to finish before sending it to the device buffer.
sleep(1);
Send data to device buffer of DAQ so that it can be read by the interface board.
ibwrt(DAQ, "FETCH? \n", 8L);
Read what is in the device buffer.
ibrd(DAQ, ReadBuffer, 15L);
Convert readbuffer to floating point and place in variable address.
sscanf(ReadBuffer, "%f", &temp);
Print thermocouple measurement to screen and then to file.
printf("Water bath temperature in Celsius: %f\n", temp);
fprintf(fp," %f\n", temp);
The following commands are for 4-wire resistance measurements. These commands
replace the temperature commands for thermocouples.
Configure DAQ for four-wire ohm measurement.
ibwrt(DAQ, "CONF:FRES AUTO,(@101) \n", 24L);
Set time length of scan.
ibwrt(DAQ, "SENS:FRES:NPLC 20,(@101) \n", 27L);
The following commands are for voltage measurements. These commands replace
the temperature commands for thermocouples.
Configure DAQ for DC voltage measurement.
ibwrt(DAQ, "CONF:VOLT:DC AUTO,(@101) \n", 27L);
Set time length of scan.
ibwrt(DAQ, "SENS:VOLT:NPLC 20,(@101) \n", 27L);